A liquid crystal display device includes a thin film transistor substrate for driving, a color filter substrate for displaying colors, and a liquid crystal provided between the substrates.
A distance between the thin film transistor substrate and the color filter substrate, that is, a cell gap is maintained constant to obtain a uniform screen on the liquid crystal display device. A spacer functions to maintain the distance between the substrates constant.
Examples of a material of the spacer may include spherical silica, a polymer, surface-treated spherical silica, a surface-treated polymer, or a glass fiber piece having a constant diameter. In addition, a photo spacer may be manufactured using photosensitive material. The photo spacer is manufactured by forming a film with photosensitive material and pattering the film by a photolithographic method.
As a liquid crystal display device having the above-mentioned structure has became larger and been applied to a monitor or a television in recent years, there have been various troubles in terms of the quality and manufacturing process of a liquid crystal display device.
For example, if a large liquid crystal display device of which diagonal length is 20 inches or more is left for a predetermined time or more under high temperature and humidity while standing vertically, white strips are formed on the lower side of the liquid crystal display device. These are called gravity defects.
The amount of liquid crystal in the liquid crystal display device may be decreased to solve the gravity defects. However, in this case, there is a problem in that the durability of the liquid crystal display device deteriorates.
Accordingly, the amount of liquid crystal in the liquid crystal display device should be in a predetermined range, and the predetermined range is called a liquid crystal margin. The liquid crystal margin is affected by mechanical properties of the spacer.
That is, if it is possible to prevent the durability from deteriorating even though the amount of liquid crystal is small, the liquid crystal margin is increased and it is possible to minimize defects during the manufacture to improve the durability of the liquid crystal display device.
The spacer, which is manufactured by a method widely known at present, has other problems in that the spacer may be lost during a rubbing process and may be detached by a strong external force.
Several minutes are generally taken to perform the rubbing process that makes a thin film for aligning liquid crystal, that is, an alignment film have anisotropy. The intensity of the rubbing may be increased to reduce the time taken to perform the rubbing process.
In this case, the spacer may be separated due to friction, and pixels of a region corresponding to the spacer do not function normally and are observed as a white spot, which causes defects.
Further, even when strong impact is applied from the outside, cracks are formed at a weak portion between the spacer and a lower support film, so that the spacer is detached.
The size of the spacer may be increased or the adhesive strength thereof may be improved in order to prevent this. However, in the case of the former, since the maximum size of the spacer has already been determined according to an aperture ratio of design and a dielectric constant, it is difficult to increase the size of the spacer. In the case of the latter, there is a problem in that the stability of a material of the spacer deteriorates.